Systems and Methods for Optimizing Spectral Resolution for a Hearing System

ABSTRACT

An exemplary sound processor is configured to direct a cochlear implant to apply standard electrical stimulation representative of frequencies in an audio signal that are within an upper region to a cochlea of a first ear of a recipient by way of a plurality of electrodes in accordance with a frequency allocation table that maps frequencies in the upper region of the audible frequency range of the recipient to the plurality of electrodes, the upper region of the audible frequency range comprising frequencies above and including a cutoff frequency, and direct the cochlear implant to apply electrical stimulation representative of frequencies in the audio signal that are within a lower region of the audible frequency range to the cochlea of the first ear by way of a most apical electrode and one or more compensating electrodes included in the plurality of electrodes in accordance with an electrode stimulation configuration.

RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 17/864,847, filed Jul. 14, 2022, which is acontinuation application of U.S. patent application Ser. No. 16/525,841,filed Jul. 30, 2019, and issued as U.S. Pat. No. 11,433,236, each ofwhich is hereby incorporated by reference in its entirety.

BACKGROUND INFORMATION

A cochlear implant system conventionally provides electrical stimulationrepresentative of audio content in accordance with a frequencyallocation table that maps frequencies within an audible frequency rangeto a plurality of electrodes located within a recipient's cochlea. Forexample, to present audio content having a certain frequency to therecipient, the cochlear implant system provides electrical stimulationby way of a certain electrode to which the certain frequency has beenmapped in a frequency allocation table.

Conventionally, frequencies within the audible frequency range that arebelow a place pitch of the most apical electrode (i.e., below afrequency that corresponds to a position within the cochlea at which themost apical electrode is located) are mapped to the most apicalelectrode in the frequency allocation table. This allows theserelatively low frequencies to be presented to a recipient of a cochlearimplant system. However, such a mapping disadvantageously increases thespectral distance between each of the mapped electrodes, therebyreducing spectral resolution for the cochlear implant system (e.g., byreducing the ability of the recipient to distinguish between frequenciesrepresented by electrical stimulation applied by way of the electrodes).

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate various embodiments and are a partof the specification. The illustrated embodiments are merely examplesand do not limit the scope of the disclosure. Throughout the drawings,identical or similar reference numbers designate identical or similarelements.

FIGS. 1A-1C illustrate exemplary hearing systems according to principlesdescribed herein.

FIG. 2 illustrates an exemplary implementation of a cochlear implantsystem according to principles described herein.

FIG. 3 illustrates an exemplary implementation of a hearing deviceaccording to principles described herein.

FIG. 4 illustrates an exemplary implementation of a bimodal implantsystem according to principles described herein.

FIG. 5 illustrates a schematic structure of the human cochlea accordingto principles described herein.

FIGS. 6-7 illustrate exemplary mappings between frequencies in anaudible frequency range and electrodes that may be defined by afrequency allocation table according to principles described herein.

FIG. 8 illustrates exemplary gain parameters that may be employed toimplement a phantom electrical stimulation configuration according toprinciples described herein.

FIG. 9 shows an exemplary configuration in which a fitting device iscommunicatively coupled to a hearing system according to principlesdescribed herein.

FIG. 10 shows an exemplary mapping of frequencies within an upper regionof a audible frequency range to electrodes according to principlesdescribed herein.

FIG. 11 illustrates an exemplary method according to principlesdescribed herein.

FIG. 12 illustrates an exemplary computing device according toprinciples described herein.

DETAILED DESCRIPTION

Systems and methods for optimizing spectral resolution for a hearingsystem are described herein. For example, a system may include a soundprocessor associated with a first ear of a recipient and configured tocontrol an operation of a cochlear implant associated with the firstear. The sound processor may be configured to maintain datarepresentative of a frequency allocation table that maps frequencies inan upper region of an audible frequency range to a plurality ofelectrodes located within a cochlea of the first ear. The upper regionof the audible frequency range includes frequencies above and includinga cut-off frequency. A lower region of the audible frequency rangeincludes frequencies below the cut-off frequency. As described herein,the frequencies in the lower region are not included in the frequencyallocation table. Accordingly, when the sound processor receives anaudio signal representative of audio content presented to the recipient,the sound processor may direct a cochlear implant to apply standardelectrical stimulation representative of frequencies in the audio signalthat are within the upper region of the audible frequency range to thecochlea of the first ear by way of the plurality of electrodes inaccordance with the frequency allocation table. For frequencies in theaudio signal that are in the lower region of the audible frequencyrange, the sound processor may direct the cochlear implant to applyphantom electrical stimulation representative of these frequencies tothe cochlea of the first ear by way of a most apical electrode and oneor more compensating electrodes in accordance with a phantom electrodestimulation configuration.

As used herein, “standard electrical stimulation” applied by way of anelectrode refers to electrical stimulation configured to convey (e.g.,cause a recipient to perceive) a frequency mapped to the electrode in afrequency allocation table. For example, the standard electricalstimulation may be focused only to a location within the cochlear tissueproximate (e.g., nearby, immediately surrounding, etc.) a location wherethe electrode is positioned. The standard electrical stimulation mayadditionally or alternatively be focused to a location within thecochlear tissue that is in between locations that correspond to wheretwo or more electrodes are positioned (e.g., by using current steering).

In contrast, “phantom electrical stimulation” is configured to convey(e.g., cause a recipient to perceive) a frequency that is not mapped toan electrode in the frequency allocation table. For example, inaccordance with the systems and methods described herein, phantomelectrical stimulation applied by way of the most apical electrode andone or more compensating electrodes adjacent to the most apicalelectrode may convey a frequency or pitch that is lower than thefrequency mapped to the most apical electrode in the frequencyallocation table.

By not including the frequencies in the lower region of the audiblefrequency range in the frequency allocation table and instead conveyingthese frequencies using phantom electrical stimulation, the systems andmethods described herein may increase the number of electrodes peroctave in the upper region of the audible frequency range. This mayfacilitate increased spectral resolution in this region for a recipientof the cochlear implant system. Moreover, by using phantom electricalstimulation to convey frequencies in the lower frequency region of theaudible frequency range (and, in some cases, a hearing device configuredto provide acoustic stimulation representative of these frequencies),sound quality may be maintained or enhanced compared to conventionalcochlear implant system configurations.

FIGS. 1A-1C illustrate exemplary hearing systems 100 (i.e., hearingsystems 100-1 through 100-3) that may be configured to implement thesystems and methods described herein.

As shown in FIG. 1A, hearing system 100-1 includes a cochlear implantsystem 102 configured to receive an audio signal and apply electricalstimulation representative of the audio signal to a recipient ofcochlear implant system 102. An exemplary cochlear implant system 102 isdescribed herein. In the configuration shown in FIG. 1A, cochlearimplant system 102 is associated with a single ear of the recipient andis the only hearing prosthesis included in hearing system 100-1. Hence,hearing system 100-1 may be referred to as a unilateral and/or singlemode hearing system.

As shown in FIG. 1B, hearing system 100-2 includes both cochlear implantsystem 102 and a hearing device 104. As described in FIG. 1A, cochlearimplant system 102 is configured to receive an audio signal and applyelectrical stimulation representative of the audio signal to a recipientof cochlear implant system 102. Hearing device 104 may be configured toreceive the same audio signal (or a different audio signalrepresentative of the same audio content represented by the audio signalreceived by cochlear implant system 102) and apply acoustic stimulationrepresentative of the audio signal to the recipient. An exemplaryhearing device 104 configured to provide acoustic stimulation isdescribed herein. In the configuration shown in FIG. 1B, cochlearimplant system 102 was associated with a first ear of the recipient andhearing device 104 is associated with a second ear of the recipient.Hence, hearing system 100-2 may be referred to as a bimodal hearingsystem.

As shown in FIG. 1C, hearing system 100-3 includes a bimodal implantsystem 106 configured to receive an audio signal and apply bothelectrical and acoustic stimulation representative of the audio signalto a recipient. Bimodal implant system 106 is associated with a singleear of the recipient and therefore provides the electrical and acousticstimulation to the same ear. An exemplary bimodal implant system 106 isdescribed herein.

A bimodal hearing system, such as hearing systems 100-2 and 100-3, maybe useful in cases where the recipient has some degree of residualhearing in a lower frequency region. This will be described in moredetail below.

FIG. 2 illustrates an exemplary implementation of cochlear implantsystem 102. As shown, cochlear implant system 102 may include amicrophone 202, a sound processor 204, a headpiece 206 having a coildisposed therein, a cochlear implant 208, and an electrode lead 210.Electrode lead 210 may include an array of electrodes 212 disposed on adistal portion of electrode lead 210 and that are configured to beinserted into a cochlea of a recipient to stimulate the cochlea when thedistal portion of electrode lead 210 is inserted into the cochlea. Oneor more other electrodes (e.g., including a ground electrode, notexplicitly shown) may also be disposed on other parts of electrode lead210 (e.g., on a proximal portion of electrode lead 210) to, for example,provide a current return path for stimulation current generated byelectrodes 212 and to remain external to the cochlea after electrodelead 210 is inserted into the cochlea. As shown, electrode lead 210 maybe pre-curved so as to properly fit within the spiral shape of thecochlea. Additional or alternative components may be included withincochlear implant system 102 as may serve a particular implementation.

As shown, cochlear implant system 102 may include various componentsconfigured to be located external to a recipient including, but notlimited to, microphone 202, sound processor 204, and headpiece 206.Cochlear implant system 102 may further include various componentsconfigured to be implanted within the recipient including, but notlimited to, cochlear implant 208 and electrode lead 210.

Microphone 202 may be configured to detect audio signals presented tothe user. Microphone 202 may be implemented in any suitable manner. Forexample, microphone 202 may include a microphone that is configured tobe placed within the concha of the ear near the entrance to the earcanal, such as a T-MIC™ microphone from Advanced Bionics. Such amicrophone may be held within the concha of the ear near the entrance ofthe ear canal during normal operation by a boom or stalk that isattached to an ear hook configured to be selectively attached to soundprocessor 204. Additionally or alternatively, microphone 202 may beimplemented by one or more microphones disposed within headpiece 206,one or more microphones disposed within sound processor 204, one or morebeam-forming microphones, and/or any other suitable microphone as mayserve a particular implementation.

Sound processor 204 may be configured to direct cochlear implant 208 togenerate and apply electrical stimulation (also referred to herein as“stimulation current”) representative of one or more audio signals(e.g., one or more audio signals detected by microphone 202, input byway of an auxiliary audio input port, input by way of a clinician'sprogramming interface (CPI) device, etc.) to one or more stimulationsites associated with an auditory pathway (e.g., the auditory nerve) ofthe recipient. Exemplary stimulation sites include, but are not limitedto, one or more locations within the cochlea, the cochlear nucleus, theinferior colliculus, and/or any other nuclei in the auditory pathway. Tothis end, sound processor 204 may process the one or more audio signalsin accordance with a selected sound processing strategy or program togenerate appropriate stimulation parameters for controlling cochlearimplant 208. Sound processor 204 may be housed within any suitablehousing (e.g., a behind-the-ear (“BTE”) unit, a body worn device,headpiece 206, and/or any other sound processing unit as may serve aparticular implementation).

In some examples, sound processor 204 may wirelessly transmitstimulation parameters (e.g., in the form of data words included in aforward telemetry sequence) and/or power signals to cochlear implant 208by way of a wireless communication link 214 between headpiece 206 andcochlear implant 208 (e.g., a wireless link between a coil disposedwithin headpiece 206 and a coil physically coupled to cochlear implant208). It will be understood that communication link 214 may include abi-directional communication link and/or one or more dedicateduni-directional communication links.

Headpiece 206 may be communicatively coupled to sound processor 204 andmay include an external antenna (e.g., a coil and/or one or morewireless communication components) configured to facilitate selectivewireless coupling of sound processor 204 to cochlear implant 208.Headpiece 206 may additionally or alternatively be used to selectivelyand wirelessly couple any other external device to cochlear implant 208.To this end, headpiece 206 may be configured to be affixed to therecipient's head and positioned such that the external antenna housedwithin headpiece 206 is communicatively coupled to a correspondingimplantable antenna (which may also be implemented by a coil and/or oneor more wireless communication components) included within or otherwiseassociated with cochlear implant 208. In this manner, stimulationparameters and/or power signals may be wirelessly transmitted betweensound processor 204 and cochlear implant 208 via communication link 214.

Cochlear implant 208 may include any suitable type of implantablestimulator. For example, cochlear implant 208 may be implemented by animplantable cochlear stimulator. Additionally or alternatively, cochlearimplant 208 may include a brainstem implant and/or any other type ofcochlear implant that may be implanted within a recipient and configuredto apply stimulation to one or more stimulation sites located along anauditory pathway of a recipient.

In some examples, cochlear implant 208 may be configured to generateelectrical stimulation representative of an audio signal processed bysound processor 204 (e.g., an audio signal detected by microphone 202)in accordance with one or more stimulation parameters transmittedthereto by sound processor 204. Cochlear implant 208 may be furtherconfigured to apply the electrical stimulation to one or morestimulation sites (e.g., one or more intracochlear regions) within therecipient via electrodes 212 disposed along electrode lead 210. In someexamples, cochlear implant 208 may include a plurality of independentcurrent sources each associated with a channel defined by one or more ofelectrodes 212. In this manner, different stimulation current levels maybe applied to multiple stimulation sites simultaneously by way ofmultiple electrodes 212.

FIG. 3 illustrates an exemplary implementation of hearing device 104. Asshown, hearing device may be communicatively coupled to a microphone 302configured to generate an audio signal representative of audio contentpresented to a recipient of hearing device 14. A receiver 304 (alsocalled a speaker or loudspeaker) is also communicatively coupled tohearing device 104. In this configuration, hearing device 104 mayprovide acoustic stimulation representative of an audio signal output bymicrophone 302 by way of receiver 304. While microphone 302 and speaker304 are shown to be communicatively coupled to hearing device 104, itwill be recognized that microphone 302 and speaker 304 may alternativelybe integrated into hearing device 104.

Hearing device 104 may be implemented by any suitable device configuredto provide acoustic stimulation. For example, hearing device 104 may beimplemented by a hearing aid configured to amplify sound presented to arecipient of hearing device 104.

FIG. 4 illustrates an exemplary implementation of bimodal implant system106. As shown, bimodal implant system 106 is similar to cochlear implantsystem 102. However, bimodal implant system 106 further includes anacoustic stimulation generator 402 configured to generate acousticstimulation representative of an audio signal received by soundprocessor 204. Sound processor 204 may be configured to apply theacoustic stimulation to the recipient by way of a receiver 404. Hence,bimodal implant system 106 is configured to provide both acousticstimulation and electrical stimulation representative of audio contentpresented to the recipient of bimodal implant system 106.

FIG. 5 illustrates a schematic structure of the human cochlea 500 intowhich electrode lead 110 may be inserted. As shown in FIG. 5 , cochlea500 is in the shape of a spiral beginning at a base 502 and ending at anapex 504. Within cochlea 500 resides auditory nerve tissue 506, which isdenoted by Xs in FIG. 5 . The auditory nerve tissue 506 is organizedwithin the cochlea 500 in a tonotopic manner. Relatively low frequenciesare encoded at or near the apex 504 of the cochlea 500 (referred to asan “apical region”) while relatively high frequencies are encoded at ornear the base 502 (referred to as a “basal region”). Hence, electricalstimulation applied by way of electrodes disposed within the apicalregion (i.e., “apical electrodes”) may result in the recipientperceiving relatively low frequencies and electrical stimulation appliedby way of electrodes disposed within the basal region (i.e., “basalelectrodes”) may result in the recipient perceiving relatively highfrequencies. The delineation between the apical and basal electrodes ona particular electrode lead may vary depending on the insertion depth ofthe electrode lead, the anatomy of the recipient's cochlea, and/or anyother factor as may serve a particular implementation.

FIG. 6 illustrates an exemplary mapping between frequencies in anaudible frequency range 602 and electrodes 212 (i.e., electrodes 212-1through 212-16) that may be defined by a frequency allocation table. Asdescribed herein, the frequency allocation table may be used by soundprocessor 202 to direct cochlear implant 208 to apply electricalstimulation representative of various frequencies included in an audiosignal.

For purposes of this example, audible frequency range 602 includes arange of frequencies including and in between 250 Hz and 16 kHz. Each ofthese frequencies may be audible to a person with normal hearing. Insome examples, the frequencies in audible frequency range 602 are alsoaudible to a hearing impaired recipient of a hearing system, such as oneof the hearing systems 100 described herein. It will be recognized thatsome frequencies lower than 250 Hz and some frequencies above 16 kHz maybe included in audible frequency range 602, depending on the particularperson and/or listening scenario as may serve a particularimplementation.

In the example of FIG. 6 , electrode 212-1 is the most apical electrodeon electrode lead 210. In other words, electrode 212-1 is the mostdistally located electrode on electrode lead 210 such that whenelectrode lead 210 is inserted into the cochlea, electrode 212-1 islocated closest to the apex of the cochlea. Electrode 212-16 is the mostbasal electrode on electrode lead 210. In other words, electrode 212-16is the most proximally located electrode on electrode lead 210 such thatwhen electrode lead 210 is inserted into the cochlea, electrode 212-16is located closest to the base of the cochlea.

Once implanted within the cochlea, electrodes 212 may each be located ata different intracochlear location that corresponds to a particularplace pitch 604. As used herein, a “place pitch” associated with aparticular intracochlear location refers to a frequency that isperceived by the recipient when the intracochlear location is stimulatedwith electrical stimulation by an electrode 212 at the intracochlearlocation. For example, as shown, electrode 212-1 is located at anintracochlear location associated with a place pitch of approximately700 Hz and electrode 212-16 is located at an intracochlear locationassociated with a place pitch of approximately 14 kHz.

Arrows (e.g., arrow 606-1 through arrow 606-16) represent mappingsdefined by a frequency allocation table between various frequencies inaudible frequency range 602 and electrodes 212. As shown, frequencies inthe audible frequency range that are below the place pitch associatedwith the most apical electrode 212-1 are mapped to electrodes 212-1through 212-3. Frequencies in the audible frequency range that aregreater than the place pitch associated with the most apical electrode212-1 are mapped to electrodes 212-4 through 212-16. In some examples,multiple frequencies may be mapped to a single electrode 212 or tomultiple electrodes 212. For example, intermediate frequencies inbetween the frequency shown as being mapped to electrode 212-1 and thefrequency shown as being mapped to electrode 212-2 may be mapped to oneor both of electrodes 212-1 and 212-2. In this example, current steeringor some other standard electrical stimulation configuration may be usedto convey these intermediate frequencies.

The mapping shown in FIG. 6 disadvantageously increases the spectraldistance between each of the mapped electrodes, thereby reducingspectral resolution for cochlear implant system 102 (e.g., by reducingthe ability of the recipient to distinguish between frequenciesrepresented by electrical stimulation applied by way of electrodes 212).

Accordingly, in accordance with the systems and methods describedherein, only frequencies included in an “upper region” of audiblefrequency range 602 are mapped to electrodes 212, while frequenciesincluded in a “lower region” of audible frequency range 602 are notmapped to electrodes 212. Hence, as described herein, standardelectrical stimulation is not used to convey these lower regionfrequencies to a recipient of hearing system 100.

To illustrate, FIG. 7 shows an exemplary mapping between frequencies inaudible frequency range 602 and electrodes 212 that may be defined by afrequency allocation table in accordance with the systems and methodsdescribed herein. As shown, audible frequency range 602 may be dividedinto an upper region 702 and a lower region 704. Upper region 702includes a cutoff frequency 706 and frequencies above cutoff frequency706. Lower region 704 includes frequencies below cutoff frequency 706.In the example of FIG. 7 , the cutoff frequency 706 is approximately 700Hz. Hence, upper region 702 includes frequencies between and including700 Hz and 16 kHz, and lower region 702 includes frequencies below 700Hz.

Cutoff frequency 706 may be set to be any suitable frequency that isgreater than a lower bound (e.g., 250 Hz) of audible frequency range602. In some examples, cutoff frequency 706 is at least a frequencyoctave above the lower bound of audible frequency range 602 so thatphantom electrical stimulation may be used to convey at least thefrequency octave to the recipient, as will be described in more detailbelow. Various ways that may be used to specify cutoff frequency 706 aredescribed herein.

As shown, only the frequencies included in upper region 702 are mappedto electrodes 212. For example, cutoff frequency 706 is mapped toelectrode 212-1. Other frequencies in upper region 702 are also mappedto electrodes 212.

In some examples, each electrode 212 is mapped to a frequency equal to aplace pitch of the electrode. For example, FIG. 7 shows that a frequencyof approximately 700 Hz, which corresponds to a place pitch of electrode212-1, is mapped to electrode 212-1. Each of the other electrodes 212 ismapped to a frequency equal to its corresponding place pitch, asindicated by the vertical arrows 708-1 through 708-16 in FIG. 7 . Anyother suitable mapping between frequencies in upper region 702 ofaudible frequency range 602 to electrodes 212 may be used as may serve aparticular implementation.

In this configuration, sound processor 204 may be configured to directcochlear implant 210 to apply standard electrical stimulationrepresentative of frequencies in an audio signal that are within upperregion 702 to a cochlea of a recipient by way of electrodes 212 inaccordance with the mapping defined by the frequency allocation tablerepresented in FIG. 7 . The standard electrical stimulation may includemonopolar stimulation, multipolar (e.g., bipolar) stimulation, currentsteering, and/or any other type of stimulation other than phantomelectrical stimulation.

In contrast, based on the mapping illustrated in FIG. 7 , standardelectrical stimulation is not used to convey frequencies in lower region704. Rather, sound processor 204 is configured to direct cochlearimplant 210 to convey frequencies in lower region 704 by applyingphantom electrical stimulation by way of a phantom stimulation channel710 in accordance with a phantom electrode stimulation configuration.Phantom stimulation channel 710 comprises the most apical electrode212-1 and one or more compensating electrodes 212. In some examples,compensating electrodes 212 are adjacent to most apical electrode 212-1(e.g., electrode 212-2 and/or electrode 212-3).

As described herein, phantom electrical stimulation is configured toconvey (e.g., cause a recipient to perceive) a frequency that is notmapped to an electrode in a frequency allocation table (e.g., in afrequency allocation table that has the mapping illustrated in FIG. 7 ).For example, phantom electrical stimulation applied by way of mostapical electrode 212-1 and one or more compensating electrodes adjacentto the most apical electrode may convey a frequency or pitch that islower than the frequency mapped to most apical electrode 212-1 in thefrequency allocation table.

Sound processor 204 may be configured to direct cochlear implant 110 toapply phantom electrical stimulation by directing cochlear implant 210to apply a main stimulation current by way of the most apical electrode212-1, directing cochlear implant 210 to concurrently apply, while themain stimulation current is being applied by way of the most apicalelectrode 212-1, a compensation stimulation current by way of the one ormore compensating electrodes (e.g., electrodes 212-2 and/or 212-3), andoptimizing an amount of the compensation stimulation current to resultin the frequencies in the audio signal that are within lower region 704of audible frequency range 602 being presented to the recipient. Phantomelectrical stimulation is described in more detail in U.S. Pat. No.9,056,205, the contents of which are incorporated herein by reference intheir entirety.

FIG. 8 illustrates exemplary gain parameters that may be employed toimplement a phantom electrical stimulation configuration in accordancewith the systems and methods described herein. In this example,electrode 212-1 is the sole compensating electrode. As depicted in FIG.8 , sound processor 204 may adjust relative gain levels of gainparameters 802-1 and 802-2 corresponding to compensating electrode 212-2and most apical electrode 212-1, respectively, such that a frequencyperceived by a recipient is substantially identical to a frequency in anaudio signal that is within lower region 704. Gain parameter 802-1 mayrepresent a level of compensation stimulation current applied by way ofcompensating electrode 212-1 and gain parameter 802-2 may represent alevel of main stimulation current applied by way of most apicalelectrode 212-1.

In some examples, gain parameters 802-1 and 802-2 may be configured inaccordance with a selected ratio of compensation stimulation current tomain stimulation current corresponding to the particular frequency inthe incoming audio signal. Additionally, gain parameters 802-1 and 802-2may be adjusted such that the total current applied to electrodes 212-1and 212-2 is substantially at the most comfortable current level. Insome examples, the compensation stimulation current is out-of-phase withmain current (e.g., by 180 degrees). The compensation stimulationcurrent may additionally or alternatively have a polarity opposite thatof the main stimulation current.

Frequencies in lower region 704 of audible frequency range 602 mayadditionally be conveyed to a recipient in any other suitable manner.For example, in cases where a recipient is associated with bimodalhearing system 100-2, frequencies in lower region 704 of audiblefrequency range 602 may additionally be conveyed by way of hearingdevice 104. In these cases, hearing device 104 may receive the sameaudio signal received by cochlear implant system 102 (e.g., by detectingthe audio signal with a microphone and/or receiving the audio signal byway of an auxiliary audio input, etc.) and direct receiver 304 to applyacoustic stimulation representative of the frequencies in the audiosignal that are in lower region 704 to the recipient. In this manner,low frequency content may be conveyed to the recipient using bothphantom electrical stimulation (at one ear) and acoustic stimulation (atthe other ear). This may increase the ability of the recipient toperceive the low frequency content.

As another example, a recipient may be associated with bimodal hearingsystem 100-3. In this example, in addition to directing cochlear implant210 to convey frequencies in lower region 704 by applying phantomelectrical stimulation way of phantom stimulation channel 710, soundprocessor 204 may direct receiver 404 to apply acoustic stimulationrepresentative of the frequencies in lower region 704 to the same ear ofrecipient.

Data representative of a frequency allocation table, such as thefrequency allocation table illustrated by the mapping shown in FIG. 7 ,may be maintained by sound processor 204 in any suitable manner. Forexample, data representative of a frequency allocation table may bestored by sound processor 204 in memory located within sound processor204. The data representative of the frequency allocation table may beadditionally or alternatively accessed by sound processor 204 in anyother suitable manner.

A frequency allocation table may be specified in any suitable manner.For example, sound processor 204 may automatically specify (e.g.,modify, update, program, or otherwise set) a frequency allocation tablebased on one or more characteristics of a recipient, one or more programsettings of sound processor 204, and/or any other factor.

A frequency allocation table may additionally or alternatively bespecified by a computing device external to sound processor 204. Forexample, FIG. 9 shows an exemplary configuration in which a fittingdevice 900 is communicatively coupled to hearing system 100. Asdescribed herein, fitting device 900 may be configured to specify afrequency allocation table and transmit data representative of thefrequency allocation table to hearing system 100 (e.g., to soundprocessor 204). Fitting device 900 may be implemented by any suitablecomputing device, such as a desktop computer, a laptop computer, atablet computer, a mobile phone, etc.

As shown, fitting device 900 may include, without limitation, a storagefacility 902 and a processing facility 904 selectively andcommunicatively coupled to one another. Facilities 902 and 904 may eachinclude or be implemented by hardware and/or software components (e.g.,processors, memories, communication interfaces, instructions stored inmemory for execution by the processors, etc.).

Storage facility 902 may maintain (e.g., store) executable data used byprocessing facility 904 to perform any of the operations describedherein. For example, storage facility 902 may store instructions 906that may be executed by processing facility 904 to perform any of theoperations described herein. Instructions 906 may be implemented by anysuitable application, software, code, and/or other executable datainstance.

Processing facility 904 may be configured to perform (e.g., executeinstructions 906 stored in storage facility 902 to perform) variousfitting operations with respect to hearing system 100. For example,processing facility 904 may be configured to set one or more parametersthat govern an operation of one or more components of hearing system100.

Fitting device 900 may be selectively and communicatively coupled tohearing system 100 by way of a communication channel 908. For example,fitting device 900 may be connected by way of a wired and/or wirelessconnection to sound processor 204. While communicatively coupled tohearing system 100, fitting device 900 may transmit data to hearingsystem 100 (e.g., to sound processor 204). For example, fitting device900 may transmit data representative of a frequency allocation table tosound processor 204. Sound processor 204 may receive and store the datain any suitable manner.

Fitting device 900 may specify the frequency allocation table in anysuitable manner. For example, fitting device 900 may set a value forcutoff frequency 706 and map the cutoff frequency to most apicalelectrode 212-1. Fitting device 900 may set the value for cutofffrequency 706 in any suitable manner. For example, fitting device 900may access data representative of a computerized tomography (CT) scan(or other medical imaging modality) of the recipient's cochlea whileelectrode lead 210 is located within the cochlea. Based on the CT scan,fitting device 900 may identify a place pitch of most apical electrode212-1 and designate the place pitch as cutoff frequency 706. Fittingdevice 900 may identify the place pitch of most apical electrode 212-1based on the CT scan in any suitable manner.

In some examples, fitting device 900 may be configured to specify thefrequency allocation table by identifying a frequency region withinaudible frequency range 602 that has poor spectral resolution for theparticular recipient. Fitting device 900 may then map frequencies withinthis frequency region to multiple electrodes 212.

To illustrate, FIG. 10 shows an exemplary mapping of frequencies withinupper region 702 of audible frequency range 602 to electrodes 212. FIG.10 is similar to FIG. 7 , except that in FIG. 10 , a frequency region1002 that has poor spectral resolution for the recipient has beenidentified. As shown, frequencies in this region 1002 are mapped to moreelectrodes than they are in FIG. 7 . In particular, frequencies withinthis region 1002 are mapped to electrodes 212-5 through 212-7. In thismanner, enhanced spectral resolution may be achieved within regions thathave relatively poor native spectral resolution.

Fitting device 900 may be configured to identify a frequency region thathas poor spectral resolution for a recipient in any suitable manner. Forexample, fitting device 900 may be configured to perform variousdiagnostic tests to identify such regions.

In some examples, fitting device 900 and/or sound processor 204 may beconfigured to set a most comfortable level (“M level”) for the phantomelectrical stimulation applied by way of phantom stimulation channel710. This may be performed in any suitable manner. For example, fittingdevice 900 and/or sound processor 204 may set the M level based on a CTscan of the cochlea, a bandwidth of lower region 704, an M levelassociated with one or more of electrodes 212, and/or any other factoras may serve a particular implementation.

In some examples, sound processor 204 may be configured to implement afrequency allocation table that does not include frequencies in lowerregion 704 (e.g., a frequency allocation table that defines the mappingillustrated in FIG. 7 ) in accordance with an acclimatization heuristic.For example, sound processor 204 may further maintain an initialfrequency allocation table that maps frequencies in both upper region702 and lower region 704 to electrodes 212 (e.g., as shown in FIG. 6 ).Sound processor 204 may initially direct the cochlear implant to applystandard electrical stimulation representative of frequencies in anaudio signal that are within both upper region 702 and lower region 704in accordance with the initial frequency allocation table. Soundprocessor 204 may gradually switch from using the initial frequencyallocation table to using a frequency allocation table that does notinclude frequencies in lower region 704 (e.g., a frequency allocationtable that defines the mapping illustrated in FIG. 7 ) over time inaccordance with an acclimatization heuristic. The acclimatizationheuristic may define incremental adaptions to the initial frequencyallocation table such that, over time, sound processor 204 switches tousing the frequency allocation table that does not include frequenciesin lower region 704.

In some examples, fitting device 900 and/or sound processor 204 mayperform one or more tests to predict recipient benefit afteracclimatization. For example, one or more spectral ripple tests,behavioral tests, EEG measurements, and/or other types of tests may beperformed by fitting device 900 and/or sound processor 204 with respectto the recipient to determine how well any of the stimulation schemesdescribed herein are functioning. In response to the one or more tests,fitting device 900 and/or sound processor 204 may adjust one or moreparameters associated with hearing system 100. For example, fittingdevice 900 and/or sound processor 204 may adjust cutoff frequency 706,one or more frequency-to-electrode mappings in a frequency allocationtable, etc.

In some examples, sound processor 204 may use an own-voice detector toimprove sound quality of a recipient's own voice. For example, soundprocessor 204 may detect when the recipient himself or herself istalking. In response, sound processor 204 may adjust cutoff frequency706, one or more frequency-to-electrode mappings in a frequencyallocation table, and/or any other parameter of hearing system 100 toenhance the sound quality of the recipient's own voice.

FIG. 11 illustrates an exemplary method 1100. The operations shown inFIG. 11 may be performed by sound processor 204 and/or anyimplementation thereof. While FIG. 11 illustrates exemplary operationsaccording to one embodiment, other embodiments may omit, add to,reorder, and/or modify any of the operations shown in FIG. 11 .

In operation 1102, a sound processor maintains data representative of afrequency allocation table that maps frequencies in an upper region ofan audible frequency range to a plurality of electrodes located within acochlea of a first ear of a recipient. Operation 1102 may be performedin any of the ways described herein.

In operation 1104, the sound processor receives an audio signal.Operation 1104 may be performed in any of the ways described herein.

In operation 1106, the sound processor directs a cochlear implant toapply standard electrical stimulation representative of frequencies inthe audio signal that are within the upper region of the audiblefrequency range to the cochlea of the first ear by way of the pluralityof electrodes in accordance with the frequency allocation table.Operation 1106 may be performed in any of the ways described herein.

In operation 1108, the sound processor directs the cochlear implant toapply phantom electrical stimulation representative of frequencies inthe audio signal that are within a lower region of the audible frequencyrange to the cochlea of the first ear by way of a most apical electrodeand one or more compensating electrodes included in the plurality ofelectrodes in accordance with a phantom electrode stimulationconfiguration. Operation 1108 may be performed in any of the waysdescribed herein.

In some examples, a non-transitory computer-readable medium storingcomputer-readable instructions may be provided in accordance with theprinciples described herein. The instructions, when executed by aprocessor of a computing device, may direct the processor and/orcomputing device to perform one or more operations, including one ormore of the operations described herein. Such instructions may be storedand/or transmitted using any of a variety of known computer-readablemedia.

A non-transitory computer-readable medium as referred to herein mayinclude any non-transitory storage medium that participates in providingdata (e.g., instructions) that may be read and/or executed by acomputing device (e.g., by a processor of a computing device). Forexample, a non-transitory computer-readable medium may include, but isnot limited to, any combination of non-volatile storage media and/orvolatile storage media. Exemplary non-volatile storage media include,but are not limited to, read-only memory, flash memory, a solid-statedrive, a magnetic storage device (e.g. a hard disk, a floppy disk,magnetic tape, etc.), ferroelectric random-access memory (“RAM”), and anoptical disc (e.g., a compact disc, a digital video disc, a Blu-raydisc, etc.). Exemplary volatile storage media include, but are notlimited to, RAM (e.g., dynamic RAM).

FIG. 12 illustrates an exemplary computing device 1200 that may bespecifically configured to perform one or more of the processesdescribed herein. As shown in FIG. 12 , computing device 1200 mayinclude a communication interface 1202, a processor 1204, a storagedevice 1206, and an input/output (“I/O”) module 1208 communicativelyconnected one to another via a communication infrastructure 1210. Whilean exemplary computing device 1200 is shown in FIG. 12 , the componentsillustrated in FIG. 12 are not intended to be limiting. Additional oralternative components may be used in other embodiments. Components ofcomputing device 1200 shown in FIG. 12 will now be described inadditional detail.

Communication interface 1202 may be configured to communicate with oneor more computing devices. Examples of communication interface 1202include, without limitation, a wired network interface (such as anetwork interface card), a wireless network interface (such as awireless network interface card), a modem, an audio/video connection,and any other suitable interface.

Processor 1204 generally represents any type or form of processing unitcapable of processing data and/or interpreting, executing, and/ordirecting execution of one or more of the instructions, processes,and/or operations described herein. Processor 1204 may performoperations by executing computer-executable instructions 1212 (e.g., anapplication, software, code, and/or other executable data instance)stored in storage device 1206.

Storage device 1206 may include one or more data storage media, devices,or configurations and may employ any type, form, and combination of datastorage media and/or device. For example, storage device 1206 mayinclude, but is not limited to, any combination of the non-volatilemedia and/or volatile media described herein. Electronic data, includingdata described herein, may be temporarily and/or permanently stored instorage device 1206. For example, data representative ofcomputer-executable instructions 1212 configured to direct processor1204 to perform any of the operations described herein may be storedwithin storage device 1206. In some examples, data may be arranged inone or more databases residing within storage device 1206.

I/O module 1208 may include one or more I/O modules configured toreceive user input and provide user output. I/O module 1208 may includeany hardware, firmware, software, or combination thereof supportive ofinput and output capabilities. For example, I/O module 1208 may includehardware and/or software for capturing user input, including, but notlimited to, a keyboard or keypad, a touchscreen component (e.g.,touchscreen display), a receiver (e.g., an RF or infrared receiver),motion sensors, and/or one or more input buttons.

I/O module 1208 may include one or more devices for presenting output toa user, including, but not limited to, a graphics engine, a display(e.g., a display screen), one or more output drivers (e.g., displaydrivers), one or more audio speakers, and one or more audio drivers. Incertain embodiments, I/O module 1208 is configured to provide graphicaldata to a display for presentation to a user. The graphical data may berepresentative of one or more graphical user interfaces and/or any othergraphical content as may serve a particular implementation.

In some examples, any of the systems, computing devices, and/or othercomponents described herein may be implemented by computing device 1200.For example, storage facility 902 may be implemented by storage device1206, and processing facility 904 may be implemented by processor 1204.

In the preceding description, various exemplary embodiments have beendescribed with reference to the accompanying drawings. It will, however,be evident that various modifications and changes may be made thereto,and additional embodiments may be implemented, without departing fromthe scope of the invention as set forth in the claims that follow. Forexample, certain features of one embodiment described herein may becombined with or substituted for features of another embodimentdescribed herein. The description and drawings are accordingly to beregarded in an illustrative rather than a restrictive sense.

What is claimed is:
 1. A system comprising: a sound processor associatedwith a first ear of a recipient and configured to: direct a cochlearimplant to apply standard electrical stimulation representative offrequencies in an audio signal that are within an upper region of anaudible frequency range to a cochlea of the first ear by way of aplurality of electrodes located within the cochlea of the first ear inaccordance with a frequency allocation table that maps frequencies inthe upper region of the audible frequency range of the recipient to theplurality of electrodes, the upper region of the audible frequency rangecomprising frequencies above and including a cutoff frequency; anddirect the cochlear implant to apply electrical stimulationrepresentative of frequencies in the audio signal that are within alower region of the audible frequency range to the cochlea of the firstear by way of a most apical electrode included in the plurality ofelectrodes and one or more compensating electrodes included in theplurality of electrodes in accordance with an electrode stimulationconfiguration, the lower region of the audible frequency rangecomprising frequencies below the cutoff frequency, wherein, in thefrequency allocation table, a first electrode included in the pluralityof electrodes is mapped to a first frequency corresponding to a placepitch of the first electrode and a second electrode included in theplurality of electrodes is mapped to a second frequency corresponding toa place pitch of the second electrode.
 2. The system of claim 1, furthercomprising: a hearing device associated with a second ear of therecipient and configured to: receive the audio signal; and direct areceiver to apply, to the second ear, acoustic stimulationrepresentative of the frequencies in the audio signal that are in thelower region of the audible frequency range.
 3. The system of claim 1,wherein the sound processor is further configured to maintain datarepresentative of the frequency allocation table.
 4. The system of claim1, further comprising a fitting device configured to: be communicativelycoupled to the sound processor; specify the frequency allocation table;and transmit data representative of the frequency allocation table tothe sound processor.
 5. The system of claim 4, wherein the fittingdevice is configured to specify the frequency allocation table by:setting a value for the cutoff frequency based on a place pitch of themost apical electrode included in the plurality of electrodes; andmapping the cutoff frequency to the most apical electrode.
 6. The systemof claim 5, wherein the fitting device is configured to set the valuefor the cutoff frequency by: accessing data representative of acomputerized tomography (CT) scan of the cochlea; identifying, based onthe CT scan, the place pitch of the most apical electrode; anddesignating the place pitch as the cutoff frequency.
 7. The system ofclaim 4, wherein the fitting device is configured to specify thefrequency allocation table by: identifying a frequency region within theaudible frequency range that has poor spectral resolution for therecipient; and mapping frequencies within the frequency region tomultiple electrodes included in the plurality of electrodes.
 8. Thesystem of claim 4, wherein at least one of the sound processor and thefitting device is configured to set an M level for the electricalstimulation applied in accordance with the electrode stimulationconfiguration.
 9. The system of claim 8, wherein the setting of the Mlevel is based on at least one of a computerized tomography (CT) scan ofthe cochlea, a bandwidth of the lower region, and an M level associatedwith one or more of the plurality of electrodes.
 10. The system of claim1, wherein the directing of the cochlear implant to apply the electricalstimulation representative of the frequencies in the audio signal thatare within the lower region of the audible frequency range to thecochlea of the first ear in accordance with the electrode stimulationconfiguration comprises: directing the cochlear implant to apply a mainstimulation current by way of the most apical electrode; direct thecochlear implant to concurrently apply, while the main stimulationcurrent is being applied by way of the most apical electrode, acompensation stimulation current by way of the one or more compensatingelectrodes, and optimizing an amount of the compensation stimulationcurrent to result in the frequencies in the audio signal that are withinthe lower region of the audible frequency range being presented to therecipient.
 11. The system of claim 10, wherein the compensationstimulation current is out of phase with the main stimulation current.12. The system of claim 1, wherein the sound processor is furtherconfigured to: maintain an initial frequency allocation table that mapsfrequencies in both the upper region and the lower region to theplurality of electrodes; direct the cochlear implant to apply standardelectrical stimulation representative of frequencies in the audio signalthat are within both the upper region and the lower region to thecochlea of the first ear by way of the plurality of electrodes inaccordance with the initial frequency allocation table; and graduallyswitch from using the initial frequency allocation table to using thefrequency allocation table over time in accordance with anacclimatization heuristic.
 13. The system of claim 1, wherein the soundprocessor is further configured to: detect when the recipient istalking; and adjust, in response to detecting when the recipient istalking, at least one of the cutoff frequency and afrequency-to-electrode mapping specified in the frequency allocationtable.
 14. A system comprising: a first microphone configured to detectaudio content presented to a recipient and output a first audio signalrepresentative of the audio content; a sound processor communicativelycoupled to the first microphone and associated with a first ear of therecipient, the sound processor configured to: direct a cochlear implantto apply standard electrical stimulation representative of frequenciesin the first audio signal that are within an upper region of an audiblefrequency range to a cochlea of the first ear by way of a plurality ofelectrodes located within the cochlea of the first ear in accordancewith a frequency allocation table that maps frequencies in the upperregion of the audible frequency range of the recipient to the pluralityof electrodes, the upper region of the audible frequency rangecomprising frequencies above and including a cutoff frequency; anddirect the cochlear implant to apply electrical stimulationrepresentative of frequencies in the first audio signal that are withina lower region of the audible frequency range to the cochlea of thefirst ear by way of a most apical electrode included in the plurality ofelectrodes and one or more compensating electrodes included in theplurality of electrodes in accordance with an electrode stimulationconfiguration, the lower region of the audible frequency rangecomprising frequencies below the cutoff frequency; a second microphoneconfigured to detect the audio content presented to the recipient andoutput a second audio signal representative of the audio content; and ahearing device associated with a second ear of the recipient andconfigured to: receive, from the second microphone, the second audiosignal; and direct a receiver to apply, to the second ear, acousticstimulation representative of frequencies in the second audio signalthat are in the lower region of the audible frequency range, wherein, inthe frequency allocation table, a first electrode included in theplurality of electrodes is mapped to a first frequency corresponding toa place pitch of the first electrode and a second electrode included inthe plurality of electrodes is mapped to a second frequencycorresponding to a place pitch of the second electrode.
 15. A methodcomprising: directing, by a sound processor, a cochlear implant to applystandard electrical stimulation representative of frequencies in anaudio signal that are within an upper region of an audible frequencyrange to a cochlea of a first ear of a recipient by way of a pluralityof electrodes located within the cochlea of the first ear in accordancewith a frequency allocation table that maps frequencies in the upperregion of the audible frequency range of the recipient to the pluralityof electrodes, the upper region of the audible frequency rangecomprising frequencies above and including a cutoff frequency; anddirecting, by the sound processor, the cochlear implant to applyelectrical stimulation representative of frequencies in the audio signalthat are within a lower region of the audible frequency range to thecochlea of the first ear by way of a most apical electrode included inthe plurality of electrodes and one or more compensating electrodesincluded in the plurality of electrodes in accordance with an electrodestimulation configuration, the lower region of the audible frequencyrange comprising frequencies below the cutoff frequency, wherein, in thefrequency allocation table, a first electrode included in the pluralityof electrodes is mapped to a first frequency corresponding to a placepitch of the first electrode and a second electrode included in theplurality of electrodes is mapped to a second frequency corresponding toa place pitch of the second electrode.
 16. The method of claim 15,further comprising: receiving, by a hearing device associated with asecond ear of the recipient, the audio signal; and directing, by thehearing device, a receiver to apply, to the second ear, acousticstimulation representative of the frequencies in the audio signal thatare in the lower region of the audible frequency range.
 17. The methodof claim 15, further comprising directing, by the sound processor, areceiver to apply, to the first ear, acoustic stimulation representativeof the frequencies in the audio signal that are in the lower region ofthe audible frequency range.
 18. The method of claim 15, wherein thedirecting of the cochlear implant to apply the electrical stimulationrepresentative of the frequencies in the audio signal that are withinthe lower region of the audible frequency range to the cochlea of thefirst ear in accordance with the electrode stimulation configurationcomprises: directing the cochlear implant to apply a main stimulationcurrent by way of the most apical electrode; direct the cochlear implantto concurrently apply, while the main stimulation current is beingapplied by way of the most apical electrode, a compensation stimulationcurrent by way of the one or more compensating electrodes, andoptimizing an amount of the compensation stimulation current to resultin the frequencies in the audio signal that are within the lower regionof the audible frequency range being presented to the recipient.
 19. Themethod of claim 18, wherein the compensation stimulation current is outof phase with the main stimulation current.
 20. The method of claim 15,wherein a value for the cutoff frequency is based on a place pitch ofthe most apical electrode included in the plurality of electrodes.